Skylights provide for the transmission of natural light to the interior of buildings. Popular both in commercial and residential structures, skylights provide a pleasing and desirable source of interior illumination and reduce the consumption and expense of electricity for lighting.
One especially useful type of skylight is a tubular skylight. A tubular skylight may include an exterior dome upon the roof of the building, an interior light diffuser at the interior building ceiling, and one or more light conveyors disposed between the dome and diffuser, such as light-conveying tubes.
In some configurations, tubular skylights may be purchased as pre-assembled systems, which make installation easier and which require less construction expertise. Tubular skylights also may be used without the need for reinforcing structural supports. In some applications, tubular skylights may require less complicated construction logistics than other types of skylights.
The light tubes used to convey light between the rooftop dome and the interior light diffuser may include a highly reflective interior surface that provides high efficiency light capture. Nevertheless, it may be desirable at times for some users to block light, in whole or in part, from being transmitted through the skylight, for example, to darken a room during daylight. Alternatively, sometimes it may be desirable to reduce the amount of light being transmitted through the skylight, by varying degrees for example, when the sun is at its brightest, without otherwise completely darkening the room.
U.S. Pat. No. 7,082,726 describes one approach for reducing light transmitted through a tubular skylight. The patentee therein sought to use a butterfly valve inserted into the light tube, the butterfly valve having two semicircular elements rotating about parallel axes toward one another (to open the valve and permit light transmittance) and away from one another (to close the valve and block light transmittance). Unfortunately, the light-damper system disclosed by this reference is complicated and expensive to manufacture and to install, requiring an electrician to install the wiring for the motor, and, having multiple parts, is more prone to failure.
Accordingly, what is needed is a light damper for a tubular skylight that is easy to manufacture, easy to install, reliable in use, and simple and efficient in construction. Further, a solar-powered light damper unit is desirable to reduce operational costs.